The entire disclosure of Japanese Patent Application No. 2001-396608 filed on Dec. 27, 2001 and Japanese Patent Application No. 2002-18004 filed on Jan. 28, 2002 including specification, claims, drawings, and summary is incorporated herein by reference in its entirety.
1. Field of the Invention
This invention relates to a printing press having a drying device, which dries ink, and a printing quality checking apparatus, which checks the printed surface of a sheet of paper, on a transport path for printing products produced by printing.
2. Description of the Related Art
So far, there has been a printing press equipped with a drying device and a printing quality checking apparatus as disclosed, for example, in Japanese Unexamined Patent Publication No. 2001-287344. In this printing press, as shown in FIG. 13, printed sheets are transported along a transport path indicated by arrows in the drawing, i.e., first delivery chain 100xe2x86x92first to third transfer cylinders 101 to 103xe2x86x92second delivery chain 104, and are finally piled on a delivery pile board 106 of a delivery unit 105. On this transport path for the printed sheets, dryers (drying devices) 109 and 110 are disposed for the first transfer cylinder 101 and the second transfer cylinder 102 upstream from checking cameras (printing quality checking apparatuses) 107 and 108 in order to prevent smears during perfecting printing. Usually, an anti-setoff sheet (not shown) is wrapped round the circumferential surface of the first transfer cylinder 101.
With the above-described printing press, the checking camera 107 and the dryer 109 (and the checking camera 108 and the dryer 110) are installed at relatively close positions about 90xc2x0 apart from each other around the transfer cylinder 101 (and the transfer cylinder 102). Thus, the heat of the dryer 109 (110) adversely affects the checking camera 107 (108), causing improper operation of the checking camera 107 (108). When UV devices (drying devices for ultraviolet curing) are used as the dryers 109, 110, the checking cameras 107, 108 need to be installed normally about 1,000 mm apart from the UV devices, and at least about 500 mm apart from them.
In the case of the dryers 109, 110 using light such as ultraviolet radiation or infrared radiation, the light from the dryers 109, 110 enters the checking cameras 107, 108, resulting in the wrong detection of the checking cameras 107, 108.
Particularly at the site of grippers of the transfer cylinders 101, 102, light is reflected diffusely. The diffusely reflected light is apt to enter the checking cameras 107, 108, and wrong detection is liable to occur.
The present invention has been accomplished in the light of the above-described situations. It is the object of the invention to provide a printing quality checking apparatus of a printing press which can reliably prevent the improper operation and wrong detection of a detector without being adversely affected by heat or light from a dryer.
According to the present invention, for attaining the above object, there is provided a printing quality checking apparatus of a printing press, the printing press comprising: transport means for transporting a printing product, which has been produced by printing, to a delivery unit; a drying device for drying ink printed on the printing product transported by the transport means; and the printing quality checking apparatus for checking a printed surface of the printing product transported by the transport means, wherein a detector of the printing quality checking apparatus is provided at a position where the detector is not affected by heat of the drying device.
Thus, the improper operation and wrong detection of the detector can be prevented reliably, and the reliability of the printing quality checking apparatus can be increased.
In the printing quality checking apparatus, the detector of the printing quality checking apparatus may be provided at a position where the detector is not affected by light from the drying device.
In the printing quality checking apparatus, the printing press may be a perfecting printing press, and the drying device and the detector of the printing quality checking apparatus may be provided for each of the face side and the reverse side of the printing product.
In the printing quality checking apparatus, the transport means may be composed of at least two transport cylinders, the drying device may be provided opposing the circumferential surface of one of the transport cylinders, and the detector of the printing quality checking apparatus may be provided opposing the circumferential surface of the other transport cylinder.
In the printing quality checking apparatus, the at least two transport cylinders may have a larger diameter than the diameter of an ordinary plate cylinder.
In the printing quality checking apparatus, the transport means may be composed of at least one transport cylinder, the drying device may be provided opposing the circumferential surface of the transport cylinder, and the detection surface of the detector of the printing quality checking apparatus may be provided in a range in which light from the drying device is blocked by the transport cylinder.
In the printing quality checking apparatus, the transport means may be composed of at least one transport cylinder and at least one endless transport device, the drying device may be provided opposing the transport path of the endless transport device, and the detector of the printing quality checking apparatus may be provided opposing the circumferential surface of the transport cylinder.
In the printing quality checking apparatus, the transport means may be composed of at least one endless transport device, the drying device may be provided opposing the transport path of the endless transport device, and the detector of the printing quality checking apparatus may be provided opposing the transport path of the endless transport device, and may be provided at a position 500 mm or more apart from the position of the drying device.